Plate-type heat exchanger

[Kelly]

OK, more food for thought. Although I've bought and installed a new (to me) heat exchanger that looks to be doing a good job, in my research I was always intrigued by these plate heat exchangers available in Europe. My exchanger is the traditional "tube" type dual-pass cylinder.

My question is, do you think this could do the job? I'll include the information available with this particular model as well as a photo to get the conversation started.

Number of plates: 20
Dimensions in mm: 191/73/51.8 (without adapters)
Flow max: 4m³/h
Height of adapters: 12mm
Volume: 0.018l/plate = 0.36l
Effective exchanging surface: 0.012m² per plate = 0.24m²
Temperature range: -195°C to 225°C
Operating pressure: 20bar*
Power max: 44kW
Materials: Stainless steel AISI 304
Circuit: F1 - F3 / F4 - F2
Adapters: F1 and F3 1/2" (12.07mm) - F2 and F4 3/4" (19.05mm)
Solder material: 99.9% copper
Weight: 1.04Kg

I am running with an electronic fresh water pump (Johnson). Published maximum flow rates for this pump are at 1.6m³/h (CM30P7-1). That value seems to be OK but I don't know how much water the engine-mounted salt water pump is moving. Otherwise, the ability to exchange heat (power) is an unknown for me when comparing exchangers.

The advantages are obviously 1) weight (!) -my traditional exchanger weighs a ton 2) materials (related to weight) 3) clean flow (the literature mentions less clogging for the plate exchanger due to internal ridges mixing up the flow patterns and 4) price. The model described here goes for about 75 dollars.

[msmith10]

Kelly,
At that price I'd consider conversion of my raw-water cooled (but freshwater only) system.
Do you have any vendor information? It may be worth testing.

[Dave Neptune]

Looks good

Hey Kelly, howz things across the pond?
That certainly looks like a very good unit and as it is stainless just a bit of flushing and your back in business if it does plug up. Looks like plenty of surface area for exchanging in a small space and mounting should be quite easy.
The unit is actually soldered together and not "held" together, correct?
Who manufactures it?

Dave Neptune

[joe_db]

http://www.duramaxmarine.com/heat-plate.htm

Apparently these are used for ships, but I have yet to find anyone using them on boat-sized engines. There are tons of them on FleaBay.

[romantic comedy]

It is approximately 7 1/2 X 3 X 2 inches.. might that be big enough?

[edwardc]

This looks to be an extremely efficient design, because of the large surface area in a small volume. The engineer in me loves that.

But the sailor in me is wary. It seems that the large area is accomplished by using lots of very small passages. This may be fine when both sides of the flow are clean, conditioned liquids, but half of our heat exchangers always have raw water going thru them. Nasty, slimy, organic-laden raw water. That's why our heat exchangers always have a cleanout cap for the raw water side.

I can't help but fear that the raw-water side of one of these would get terminally clogged with goop. It's brazed shut. How would you clean it?

Is there a variation that uses gaskets and through-bolts instead of brazing?

[Dave Neptune]

Durable too.

Edward, the stainless construction would allow for repeated acid or vinegar flushes without compromising the unit. Because of the design I could see an easily fabricated permenant flush hook-up to ease the duty.

Kelly, just how much clearance is between the plates for flow?

Dave Neptune

[sastanley]

I think this unit might be good to make fresh hot water for people consumption. You have antifreeze on one side, and clean potable water on the other.

[Kelly]

...more info...

I posted this on a Friday which is not too smart as I can't follow up on the weekends...but I'll get back to this on Monday. Promise.

Dave- Things are well on this side of the pond...even felt a bit like spring today with daffodils basking in the sunshine. The days are getting longer and should allow me to get to work on my broken mast

[smosher]

One of my goals is to add the heat exchanger to my salt water cooled system.

How do you size the exchanger to the A4 ?. The one Kelly shows is real small its rough 8"x3x2. I could find a place to mount that size if its large enough to support the A4

Steve

[sastanley]

lots to consider

smosher...size is not as important as cooling capacity. If you remember Neil's trials a few years ago...he had this really beautiful Stainless HX that was at least 3" in diameter, but it turned out to be a single pass I think, and could not cool the antifreeze enough to keep the engine temps under control.

I lucked out and took a chance on an old beat-up looking 2" diameter exchanger on ebay from Sen-dure (a "compact 2T-15" if you wanted to look up the specs on their website), and it is a dual-pass and has been working well..even with 89°F raw water temps, I never got the engine temp sensor over 200°F & it usually hovered around 190°. I am not sure if the constant flow electric pump helps to keep the antifreeze moving thru or not, or if the smaller HX is just efficient enough to handle it. I also kept the t-stat in place, and didn't properly flush and clean out all of the water jacket passages like I should have. This winter I am taking care of the water jacket, and we'll see if it runs any cooler...I'd rather see numbers like 180°-185°F. A separate test may be to remove the t-stat if I want lower numbers. I was a little worried about this HX, and really wanted a 3T-12 (12" tall, and 3" diameter w/ larger fittings), but I've been pleasantly surprised with the one I have.

My point is that there are multiple aspects to consider. I also tried to reduce any choke points with no 90° elbows and liberal use of cast smooth radius fittings. I think a combination of these things helped the smaller HX keep up.

[joe_db]

Check this out:

http://www.ebay.com/itm/VOLVO-PENTA-HEAT-EXCHANGER-INSERT-AQ-GUARANTEE-85555-/290859357130?pt=Boat_Parts_Accessories_Gear&hash=item43b89193ca&vxp=mtr

Apparently Volvo did something like this.

[Kelly]

Limitations but not out for the count...

Here's a link to the site I was looking at offering the plate heat exchanger.

The unit is actually soldered together and not "held" together, correct?

Dave and Ed- The unit is actually "held together" and there are joints between the individual plates. The web site states two things that could be deal breakers: 1) the temperature difference between fluids needs to not be "too high" in order to avoid deformation of the plates (and leaking) and 2) the unit has yet to be accepted for certain certifications. I know, those are pretty vague complaints but the web site information is imperfect.

The documentation mentions "a few millimeters" for intra-plate clearances.

How do you size the exchanger to the A4 ?. The one Kelly shows is real small its rough 8"x3x2.

Steve and Romantic Comedy- I agree, the unit looks to be ridiculously small. But what counts in the end are the "Power max: 44kW" rating, strength under pressure and flow rates.

At the bottom of the description there is a note stating "if the unit is to be used with vibrating machines (boat motors) then you must use metallic pipes".

Why??

Flash info: Here's a link to the probable manufacturing site in Germany. Also, on this site, contradictory information claims that the plates are all soldered together, eliminating the leak worries...Also, units are available with fewer or more plates- with corresponding prices.

[Administrator]

This is a really interesting thread.

The dramatic difference in weight is telling us something, I think. Is the flat plate version we're looking at woefully undersized for the task? One would think that the circular cross-section of the interior tubes in a conventional HX would be the most efficient with respect to heat transfer per unit of weight. But maybe not?

I wonder if Kelly could simply ask the vendor. "Here's the scenario: Fluid on both sides is water. Hot side thruput GPM is W. Cold side thruput GPM is X. Inbound temp on the hot side is Y. Inbound temp on the cool side is Z. What are the outbound temps on both sides?

Hope somebody tries one.

Bill

[Kelly]

Bill-

I've sent a few questions off to the manufacturer. We'll see what I can get...